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Apicoplast Targeting of a Toxoplasma gondii Transmembrane Protein Requires a Cytosolic Tyrosine‐Based Motif
Author(s) -
DeRocher Amy E.,
Karnataki Anuradha,
Vaney Pashmi,
Parsons Marilyn
Publication year - 2012
Publication title -
traffic
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.677
H-Index - 130
eISSN - 1600-0854
pISSN - 1398-9219
DOI - 10.1111/j.1600-0854.2012.01335.x
Subject(s) - apicoplast , biology , transmembrane domain , transmembrane protein , microbiology and biotechnology , biochemistry , golgi apparatus , toxoplasma gondii , plastid , amino acid , chloroplast , endoplasmic reticulum , genetics , gene , receptor , antibody
Toxoplasma gondii , like most apicomplexan parasites, possesses an essential relict chloroplast, the apicoplast. Several apicoplast membrane proteins lack the bipartite targeting sequences of luminal proteins. Vesicles bearing these membrane proteins are detected during apicoplast enlargement, but the means of cargo selection remains obscure. We used a combination of deletion mutagenesis, point mutations and protein chimeras to identify a short motif prior to the first transmembrane domain of the T. gondii apicoplast phosphate transporter 1 ( APT 1) that is necessary for apicoplast trafficking. Tyrosine 16 was essential for proper localization; any substitution resulted in misdirection of APT 1 to the Golgi body. Glycine 17 was also important, with significant Golgi body accumulation in the alanine mutant. Separation of at least eight amino acids from the transmembrane domain was required for full motif function. Similarly placed YG motifs are present in apicomplexan APT 1 orthologs and the corresponding N ‐terminal domain from Plasmodium vivax was able to route T. gondii APT 1 to the apicoplast. Differential permeabilization showed that both the N ‐ and C ‐termini of APT 1 are exposed to the cytosol. We propose that this YG motif facilitates APT 1 trafficking via interactions that occur on the cytosolic face of nascent vesicles destined for the apicoplast.